University of Wisconsin-Madison Physical Sciences Lab

Holding it just right.

Friday, September 6th, 2013

Dr. Carol Mitchell is the Director of the Diagnostic Imaging Laboratory and Diagnostic Imaging Programs at UW Milwaukee. Some of the research that she is involved with requires taking a measurement with an ultrasonic sensor in each of the cells of six-cell culture plates. In order to get consistent results the operator must lower the sensor to the same depth, within a few thousandths of an inch, into each cell. She asked if PSL could help design some equipment to assist with this job.

At the heart of the device that we produced is a Starrett height gauge – an instrument for making very accurate measurements of part dimensions above a flat surface. We mounted this device to a granite surface plate and added a sensor holder in place of the height measuring probe that is normally part of the device. When the sensor is at the desired height the device is zeroed. The sensor is then lowered down in each cell so that the readout comes back to zero and a reading taken. An adjustable stop was added so that the sensor could just be lowered to the stop (the readout is then used just as a check on the sensor height). This is a faster way of reaching a consistent height.

Mike Hughes, a machinist at PSL, did much of the actual design of the device.

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